3085 Having a Skin Prick Test

Hello. Your doctor has arranged for you to have a skin prick test to find out which substances you are allergic to. If we find you are allergic to a substance then we call it an allergen. This video will tell you how to prepare, and what to expect in the test. In a skin prick test, a nurse will put drops of different potential allergens on your forearm, and then prick them into your skin to see if you develop a skin reaction. Up to twenty five substances can be tested at once. If you develop a skin reaction, this indicates that you have a sensitivity to that specific allergen. Using these results and the information from your history, your doctor will know what allergens you are allergic to, and therefore which substances you should avoid, but it does not tell us how strongly you will react to the allergen. Firstly, if you can’t attend the appointment you have been given please call us to to make alternative arrangements. If you are taking anti-histamine medication, you must stop taking it before the test. Your appointment letter will tell you what to do. You can continue taking other medications, unless your doctor tells you otherwise. On the day of your appointment, please do not use any soaps or moisturisers on your skin as these can contaminate the results. Arrive at the hospital in plenty of time so that you can park and make your way to the clinic. On arrival, please tell the receptionist that you are here. You will be called in to see the specialist nurse who will perform the test. They will explain the procedure and answer any questions you may have. The test is usually performed on your forearm, but if you have a skin condition affecting this area, the test can be done on your thigh or back. You need to roll up your sleeve and rest your arm on the table. The nurse will write numbers on your arm which relate to the allergens they want to test. As well as the allergens, two other substances are put on your skin. One causes a reaction in everybody, and the other never causes a reaction. By checking the results of these two substances, the nurse can judge whether the test is accurate. A small drop of each of the allergens is dropped onto your skin next to the corresponding number. The nurse uses a small, sharp instrument called a lancet to prick your skin. It will feel sharp but not painful, nor should it bleed. A different lancet will be used on each different allergen to prevent contamination. Once this is done, the drops of allergen can be wiped from your arm. You then have to wait ten to fifteen minutes to see the results. During this time your skin may feel itchy, but this is expected. Very rarely, people can develop a severe allergic reaction but the team undertaking the test are prepared for this and can deal with any problems if necessary. After fifteen minutes the nurse will check the results. Small red lumps called wheals will develop where you are sensitive to an allergen. The size of the wheals will be measured to gauge the scale of your reaction. The wheals will gradually fade over the next twenty minutes. The nurse will explain the results to you, and give you advice about how best to manage any allergies you have. If you have any questions about the skin prick test, please speak to your GP or one of the allergy specialists.